This invention concerns a flexible asphaltic roofing membrane comprising a mat coated with an asphaltic/olefin polymer composition which composition improves asphalt/olefin polymer compatibility while minimizing the polymer to asphalt weight ratio.
Asphaltic compositions containing propylene and/or ethylene polymers are known and used extensively in coating non-woven mat surfaces used as membranes in commercial and domestic building construction. However, attempts to overcome several objectionable characteristics associated with these coating compositions have been the subject of current research. One important disadvantage relates to the cost resulting from the relatively high concentration of polymer required to provide a good weatherability by converting the asphaltic backbone to a continuous polymeric matrix. Other objections to the current coatings reside in low compatibility between the non-polar polymer and polar asphaltic components, the staining of substrates due to undesirably high light end exudates from the asphalt and/or polymer components, their tendency to degrade upon exposure to UV light and their low degree of flexibility which often leads to fracture or peel-off of the coating.
Accordingly, it is an object of this invention to minimize or eliminate the above objections associated with roofing and siding asphaltic coatings.
Another object of the invention is to achieve a more efficient, more economical use of polymer in asphaltic coatings.
Still another object is to improve the compatibility between asphalt and polyolefins in substrate coatings.
Yet another object is to provide an economical, commercially feasible process for the manufacture of improved asphaltic coatings.
These and other objects and benefits of this invention will become apparent from the following description and disclosure.
In the following discussion, the term polymer is intended to include homo-, co- and ter-polymers unless otherwise indicated.
This invention concerns a roofing or siding membrane comprising a non-woven mat coated on at least one surface with an asphaltic composition comprising, by weight,
(a) between about 35 and about 85% asphalt;
(b) between about 1 and about 15% isotactic C2 to C3 olefin polymer, most desirably poly(propylene), utilized in a crystalline state;
(c) between about 5 and about 50% amorphous C2 to C3 olefin polymer, most desirably propylene/ethylene copolymer;
(d) between about 0.08 and about 15% of a functionalized ethylene and/or propylene polymer; said composition optionally containing (e) up to 20% of a non-functionalized ethylene/C3 to C12 xcex1-olefin copolymer and/or (f) up to 50% filler.
The invention also concerns the above novel coating composition.
In accordance with the present invention there is provided a roofing or siding membrane comprising a non-woven mat, preferable a polyester mat, coated on at least one of its top and bottom surfaces with a 0.1 to 9 mm thick layer of instant asphalt/polymer composition containing components (a) through (d) and optionally (e) and/or (f). The functionalized polymer component (d) is a homo-, co- or ter-polymer of ethylene or propylene or a mixture thereof. Suitable comonomers of the functionalized ethylene and/or propylene monomers include C4 to C12 xcex1-olefins and mixtures thereof; particularly preferred are the butene and octene comonomers. These functionalized polymers have a melt viscosity at 374xc2x0 F. of from about 200 to about 300,000 cps and can be activated with a functional moiety selected from the group of:
1. an organic nitrogen-containing group such as amino or amido as in succinimide, phthalimide, etc. and
2. an organic oxygen-containing group such as, for example, hydroxy, carboxyl, anhydride, aldehyde, epoxy, peroxy and ester.
Examples of suitable polymers of component (d) include functionalized polyethylene, polypropylene and ethylene/propylene, ethylene/butene, propylene/butene, ethylene/hexene, ethylene/octene copolymers, ethylene/propylene/butene, ethylene/propylene/octene terpolymers, ethylene/propylene/C4 to C8 dienes and the like and mixtures thereof. The most preferred functionalized polymers are the maleic anhydride functionalized C2 to C3 olefin polymers. These polymers are commercially available and include the maleic anhydride functionalized poly(propylene), e.g. POLYBOND(copyright) 3000, supplied by Crompton Corporation or FUSABOND(copyright) 353 D, supplied by DuPont Chemical Co.; the maleic anhydride functionalized poly(ethylene), e.g.
EPOLENE(copyright) G 3003 and G 3015 supplied by Eastman Chemical Co.; the maleic anhydride functionalized ethylene/propylene copolymer, e.g. FLEXOMER DEFA 1373, supplied by Dow Chemical Co. and the methacrylate functionalized propylene/ethylene/butene terpolymer, e.g. LOTADER(copyright), supplied by Autofina Corp,
Superior mat coating compositions containing filler are obtained with compositions containing, by weight, 45-65% (a); 3-5.5% (b); 8-20% (c); 0.1-2% (d); 1-5% (e) and 5-40% (f). Non-filled coating composition most effectively comprises, by weight, about 50-85% (a); 3-10% (b); 10-40% (c); 0.2-4% (d) and 1-10% (e).
Although any commercial roofing asphalt can be employed as the bitumen component (a) in the present composition, excellent results are achieved with asphalts having a softening point of between 80 and 150xc2x0 F. and from about 120-220 decimillimeters (dmm), by ASTM D5 Penetration 5 sec./100 g total weight. A particularly useful asphalt is found to be Lagoven Flux (180-200 dmm penetration) obtained from Trumbull Co. in Kearny, N.J.
The mat on which the coating composition is applied can be composed of glass and/or organic synthetic fibers including nylon, orlon, polyester fibers and the like.
The inorganic filler suitably employed in the present composition includes any of the commercially standard types, such as calcium carbonate, limestone, talc, sand, clay, stone dust, etc.
Amorphous C2 to C3 olefin polymers, as well as isotactic C2 to C3 olefin polymers and ethylene/C4 and higher alkene copolymers are discussed in U.S. Pat. Nos. 5,397,843 and 5,482,982 which disclosures are incorporated herein as describing suitable components (b), (c) and (e) for use in the present composition. Isotactic poly(propylene) and amorphous propylene copolymers are most preferred as components (b) and (c). These polymers are commercially available as amorphous poly(propylene) REXTAC(copyright) 3280, supplied by Hunstman; amorphous propylene/ethylene copolymer, e.g. EASTOFLEX(copyright) E1060, D192 and D183, supplied by Eastman Chemical Co. and REXTAC(copyright) 3585, supplied by Huntsman; isotactic poly(propylene), supplied by Sundance Co., Matrixx and Delcor Co.
It is now discovered and is indeed surprising that, to overcome the relatively poor compatibility between the asphalt and polymer components in previous formulations, only a small amount of the functionalized olefin polymer is needed and also that the addition of the functionalized component provides further benefits such as reduced asphalt and polymer exudates, an undiminished coating strength using a significantly smaller olefin to asphalt ratio and provides a flexible coating which imparts flexibility to the coated mat.
The coated mat, comprising the membrane of this invention, is marketed in rolls directly suitable for installation on either flat or pitched roofs. While the present single ply mats are preferred, multiple plied substrates are contemplated as being within the scope of this invention. Accordingly, the roofing may contain up to 6 ply layers, e.g. layers of atactic polyolefins, butadiene and styrene polymers and other multiple ply membranes used for built up roofing (BUR) and other commercial roofing or siding materials.
The present coating compositions can be economically produced by intimately mixing solid particles of the isotactic component (b) with an asphalt melt or flux maintained at a temperature of between about 275xc2x0 and about 450xc2x0 F., more desirably 350xc2x0-390xc2x0 F., and agitating the resulting mixture until the solids are dissolved. Then adding the remaining components (c), (d) and optionally (e) and/or (f). The resulting hot composition is then coated on one surface, or preferably both the top and bottom surfaces, of the mat and allowed to cool. The resulting product is flexible and can be packaged in rolls for shipment.
Having generally described the invention, reference is now had to the following examples which illustrate the best mode of the invention but which are not to be construed as limiting to the scope thereof as set forth in the accompanying claims.